As luck would have it, I have a nice one for you today. After publishing the “getting started in carpentry” article, several people started throwing around ideas on the forum for useful do-it-yourself projects. One of the most useful ones that came to mind for me was the “Jumping Box”, an exercise accessory that I only recently learned about through Mrs M’s crossfit workouts.

It’s a great first-time project to build, because it’s simple, cheap, and relatively forgiving of imperfect construction methods. Yet it also quite useful, because it can provide a lifetime of free exercise, plus it can serve as a spare chair or table, and it can even be used to generate income (more on that later).

After trying one of these things out in the Crossfit gym, I was instantly hooked. The basic idea of the box is this: It’s a 20″ high pyramid of sturdy plywood. You stand in front of it. You jump to the top of it and catch your balance. Then you jump down to the mat, bounce quickly back to the top, and regain balance.

The exercise provides a great combination of heart-pumping cardiovascular work, calf, quadricep, and hamstring muscle building, and balance and core strengthening as well. Plus it’s really fun, because hey, you’re Jumping! How often do you do that these days!? Jumping is for joy.

And it can be scaled to any degree. You can build a 12 incher or a 30 incher. I made a 20 for this article because it’s comfortable for most moderately fit people. If I want to make the exercise more strenuous, I just hold a pair of 25 pound barbell plates during the jump, as shown in the pictures (this also adds a bonus upper body component to the exercise as well).

One of the best parts of this project is that you make it from only about half of a single 4×8 sheet of plywood (I recommend 3/4″ thickness). Those sheets cost under $30 at a building supply store, so you’re really getting a great part of a home gym for about the price of a single drink on a cruise ship. So let’s get started and build this sucker.

The first step is to cut a long strip of wood that is 18.5 inches wide and the full 8 feet long. The hitch? You need to set your saw at a ten degree angle before making the two cuts to form the strip. Here’s what that looks like:

This is even easier with a table saw, but I’m showing it with a circular saw since more people have those. Even an 18V cordless saw as I’m using here has plenty of power to cut plywood.

You make two cuts, with the saw running the same direction, so you end up with a piece of wood that is a parallelogram when viewed from the end.

Next, you will be sketching trapezoid shapes on your new strip of wood. 23.5 inches at the base, 17.5 inches at the top:

Draw in your lines with a pencil and ruler (click on any of these pics for a larger version)

When you’re done sketching and ready to make the two cuts, remember to set your saw back to a zero-angle (square cut) and go for it. Then take your new trapezoid, spin it around to match the freshly cut angle on the remaining long board, line it up, and TRACE its right hand side, to give you your next cut line:

Here I rotated the first piece 180 degrees and traced it, to make a duplicate copy.

Cut that second line. Wow, you’ve already almost halfway done the cutting. But don’t go crazy and start tracing that piece again. You’ve just made the two LONG sides. Now you need to make the two SHORT sides, which allow for two plywood thicknesses, yielding a square box when you put it all together.

To accomplish this, measure across 22 inches at the bottom, and 16 inches at the top. Draw that single line, and cut out the piece. Then rotate it 180 degrees and trace it again, which will get you to this point:

Now you’ve got all four sides. You can write “Long” and “Short” on them and line them up like this:

Now you take a Short piece, add some wood glue to its end, and butt it up against the flat side of a Long piece. Be careful of those 10 degree angles on the bottom and top: you want to orient them both so that the ends sit flat on your work table and provide a flat top when assembled into a pyramid shape:

Here are two steps pasted into one picture: glue the end of a short, then stick it to the long

To make the attachment, I like to use a 16 gauge nailgun with 1.5″ nails. But if you don’t have a nail gun, you can also use 3-4 screws with a 1.5″ length as well. In this case, you’ll want to first pre-drill the holes to avoid splitting the plywood. A 1/16″ or 3/32″ drill bit might do the trick.

So you take a Long, and attach a Short. Next, attach another Short, and you’ll have this:

Then you put on the last Long, and flip the whole box over so you can trace the top and cut it out:

Attach the top, and you are pretty much ready to start Jumpin’! But you’ll probably want to consider these optional enhancements:

Interior reinforcement: For larger boxes, heavier people, or professional use (i.e. if you are building the box for a crossfit gym), cut out four 18″ sticks of 1.5″ by 1.5″ wood, and glue and screw them to the interior corners like this:

Nice Handles: Measure down 4″ from the top, in the center of the box. Then make dots 2″ to each side of that. Draw a 1.5″ circle, centered on each dot (perhaps by tracing a lid from your recycling bin). Or use a hole saw in a drill. Connect the two circles, and cut out with a jig saw. It sounds a little complicated, but really all you’re making is this:

When you’re done with the handles, the last step is simply sanding and finishing the box. I leave mine unfinished, but I am fond of a nice sanding job with a belt sander. The finished product looks like this:

Isn’t that a beauty!? .. and these things are quick to make once you get the hang of it. The first one I ever made took less than an hour, and the second one was much faster than that.

Bonus Income Generation Idea!

A confluence of events has aligned to make it possible for an entrepreneurial Mustachian to make some great side income by making these boxes for other people: The “Crossfit” workout method has taken off and become a nationwide trend. Gyms are popping up in every city. Everybody, including all the crossfit gyms, wants these boxes. But most people do not have any carpentry skills, and the boxes are too big to make and ship cost-effectively from China – or indeed to ship at all.

So, depending on features and finish, these things can easily sell for between $50 and $100. But the raw materials are about $15 and less than an hour of work (probably as low as 15 minutes per box if you streamlined production and did them in bulk).

I made my first box of this type a few weeks ago and started using it regularly for workouts. But then it disappeared from my basement – Mrs. Money Mustache had SOLD it for fifty bucks to one of her crossfit amigos! So I made a second one for this article, but there are already requests to purchase it as well. I’m not going to start cranking these things out, because that would be too much like a real job. But that leaves the door open for anyone else who would benefit from a second job, to make a few boxes on weekends. If you were a high school kid, would you rather punch keys on the Target cash register for $8 per hour, or polish your woodworking chops in your parents’ garage for closer to $50? Yeah, I thought so.

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That’s pretty darn cool. I’m on yard work duty this weekend (thanks to yesterday’s citation from the city for a messy side yard), but might have to make one of those next week. I bet the wife and kids would really dig it.

Oh yeah, thanks for pointing that out. I meant to recommend 3/4 inch in the article, so I just added it.

In the pictures, I made this box out of slightly thinner 5/8″ stuff, since it happened to be in my shed. But the box is even stronger and the material is a bit easier to attach together if you use 3/4.

I made one of these a couple years back so I thought I would chime in.

I did mine with 3/4 plywood and it’s dimensions are 20 X 24 x 28 without the angled sides. Those are common heights for prescribed Crossfit workouts and putting them all in one box eliminates the need for 3 different sizes sitting around. Having said that, the angled boxes usually stack fairly cleanly, so you could likely build all 3 sizes into a package that stacked efficiently.

Things I would change.
1) The thing is somewhat heavy, and fairly annoying to move. That is partly because mine has 6 sides instead of 5, but 5/8 plywood is probably fine. You are mostly landing directly on top of the side supports and it’s plenty strong there.
2) I cut some slits for easier carrying, but for some reason I chose to cut the slits in the 20×24 inch sides. This means the box feels a little ungainly when carrying. It is probably better to cut slits into the 28×20 or the 28×24 sides so that the long side is oriented up and down when carrying.
3) Don’t try to get fancy and cut the ends at 45 degrees to create perfectly clean lines. Mine splintered a little bit upon screwing and is just a dumb idea upon reflection.

Nice. I had the same idea and 51 questions when I saw a similar $125 plywood box at a crossfit friend’s house. It was even simpler, requiring no blade change, as it was just a rectangular prism that could be set on different faces to get the 20″ or 30″ height. It was a bit more massive since it didn’t benefit from a wider, more stable base, but it was still a box.

Now I know what it’s guts look like since he wouldn’t let me take it apart. Thanks. Any reason the braces didn’t run the full height? And no handcut dovetails?

If you wanted to get really fancy and had a v-shaped brace, you could cut the 1.5″x1.5x” ends with that same 10 degree angle, and have the top end flush to the underside of the top (glued and/or screwed) and the bottom flush to the floor… You’d need a v-shaped brace, because you’d have to cut the piece corner-to-corner with that angle, not side-to-side. Heh — hard to explain without a photo.

I made this for about $15, and I can increase the weights as needed, without having to upgrade to a new kettlebell size. I did put duct tape around the handles to make a little more comfortable than the steel. Larger-sized weights can be a little awkward.

Another easy to make innovation for the home gym so that you can do the floor press (safer to do alone than the bench and all you need are your weights and a barbell). Just screw four 2X4s together, and slap a piece of rubber matting on top to screw down and (depending on the length of your arms), just lie down and press.

With the welding skills recently posted you could also build a good set of squat stands.

Short answer: box jumps in circuit training have too high of an injury rate, a bad risk/reward ratio.

Longer answer: Any idiot can design a circuit that tires you out. See the joke site http://wodgenerator.net/ . A harder thing to do is intelligently design a circuit. One of the main considerations you should have when doing circuit training (viz: CrossFit(TM)) is what will happen on each of the exercises you’re doing when you do them in a fatigued state. High repetitions of box jumps have a couple reasonably common ways to fail: popping your Achilles tendon and missing the top (usually ends up scraping your shin terribly). Then, if you look at the specific benefits of high rep box jumps (as opposed to other exercises you could put in the circuit), you have to weigh that against injury rates. If you run a lot of circuits and track injury rates and have box jumps in a decent proportion of them, you will note that a significant proportion of your injuries come from the box jumps. If you do workouts CrossFit(TM) style, you will probably also get a fair number of torn hands. Frankly, the appropriate response, then, is to work out ways to reduce hand tearing and to eliminate box jumps from your circuits.

Box jumps are appropriately used as plyometric exercises to develop power and are therefore best used in low reps by appropriately trained athletes. But, hey, they’re fun, so, whatever.

There is also an argument to be made against high-rep snatches and such (if you want a high-rep snatching movement, do KB snatches – and if you want to do high-rep KB-to-overhead movement, do KB snatches, not the terrible overhead swing CrossFitters do).

Yeah, I kind of agree with gzt that there’s nothing magical about crossfit workouts and those WOD generator workouts look exactly like real crossfit “Workouts Of the Day”. But for the right people, the RESULTS are still magical, due solely to the motivation it creates to work really hard several times per week in the company of other people. Mrs. M. is a perfect example, as she has had great results.

Being too stubborn and independent to join an actual gym myself, I always “design” my own workouts, and I don’t jump onto tall boxes when I’m feeling exhausted and sloppy. But still, adding jumping to my workouts has been great, since I had never really done it regularly. It has been a nice surprise to my non-basketball-playing legs, and surprises mean more strength!

In what direction are you screwing the interior supports? In the picture, it looks like you’re screwing from the inside out… but the plywood is pretty thin, so you’d probably only have a bit of the tapered end of the screw in. Wouldn’t it make more sense to screw into them from the outside?

My husband made a few of these for Crossfit but never got around to doing the handle cut outs. When we relocated the movers turned them over and labeled them “planter boxes” on the forms. Just another marketing idea for anyone who is thinking about building these for profit :)

I think your jumping box is a good idea, but you have yet to make it a great idea. I’ll explain:
You should turn it into a “Jump… to CONCLUSIONS box.” You see, it would be this box that you would put on the floor… and would have different CONCLUSIONS written on it that you could JUMP TO.
I’m telling you MMM, it’s a million-dollar idea just waiting to happen. Now if you’ll excuse me, I’ve got to get back to these TPS reports…

Circular saws still freak me out. I inherited one from my dad, but haven’t been able to bring myself to use it in a project. The image of severed fingers flying through the air keep coming to my head. Given that I need my digits to be fully functional for my occupation (and to do other things) I have avoided using it thus far. My fear is probably irrational, right?

I have always hated using a circular saw. I’ve recently become more comfortable with it by being better prepared. In the past I didn’t have clamps to attach the wood securely to the saw horses. I would put heavy dumbbells on the board, but there was too much sliding. I bought some clams and that helped a lot. Best 30 to 50 I’ve spent in a long time.

I also replaced the blade that was on there. That would be first thing I would recommend to you. If you’re having trouble cutting the wood, you probably have a dull blade. Even so, I still have to psyche myself up to use the damn thing. I hate when it kicks back, which typically means I’m doing something stupid. I however have been doing amateur home improvement projects once every month or so and haven’t had any injuries, for the most part I’m very cautious.

Doing the cross fit box should be easy because you’re mostly working with thin wood. I tend not to have any problems until I start cutting compressed wood for outdoor projects.

I was trying to think of good ways to mimic the leg press machines you see at the gym. This seems to work almost the same muscles especially like you said by holding some weights in your hands while jumping.

This is actually exactly like the “Fanny Lifter” they use in the FIRM videos (mostly for women). It’s not used for jumping but just for stepping up onto slowly while holding weights, and sometimes sitting on while doing upper body lifting. Just another idea if you’re planning to sell to people who may not be into Crossfit.

Sure, you’re free to add any cross-bracing you like, but I would say it is not necessary. If you haven’t made these things before, you might be surprised at how strong they are. There’s natural strength in a pyramid shape, and the top acts as a cross-brace automatically. In fact, even the corner braces I added to this one are unnecessary, unless you throw the box around a lot or plan to balance it diagonally and jump on the corners.

as a money making idea this is great. as a workout, eh? I saw a super fit guy the other day doing jumping and huge striding (think triple jump) and other jumping exercises in the park near my home and he needed no plywood for a fantastic workout and his legs rivaled yours MMM…anyway just saying buying plywood and playing with tools is not needed to jump in a safer way to fitness…
the thought of missing and catching my shin makes me wince.
best.

I promise you the triple jumper you saw does PLENTY of other exercise to get his legs to look and perform the way they do. In fact, I’d wager he does box jumps. I know I did when I was a triple jumper in HS (along with the calisthenics you’re describing). He’s probably mostly practicing his technique when at the park, and maybe some cardio. The real power-building workouts happen in the (home) gym.

As a mini-mustachian when it comes to woodworking, I thought I’d let people know that many cities have a Tool Lending Library where you can rent saws and other tools for free (or a very low cost annual fee – ours is $10). The one in my town is part of Habitat for Humanity. Here’s a Wiki link to a list of them: http://en.wikipedia.org/wiki/List_of_tool-lending_libraries

Love the part where you say “…relatively forgiving of imperfect construction methods”… I think that “relatively” is a key word here. If my result was relative to my carpenter skills, I think I would be relatively sure that my end result would be a visit to the ER…. :)

All right people, we’re up to about 30 comments, and at least EIGHT of them have been fearful fretting ones talking about “safety”.

Come on! It’s an article about how to make a plywood box, not a DIY basejumping wingsuit!

Let’s all just relax and think about the GOOD things that come with exercise, rather than the possible bad things. This box idea is intended for people who are in good jumping condition. To be used in moderation, without excessive reps, with lots of other strengthening and stretching exercises, and blah blah blah. For those not there yet, try some walking and biking first :-)

I was taught to push off from the heels, not the toes. There are also many scary webpages depicting the horrible things that can happen to your Achilles when box jumps are performed poorly. For this reason, I jump up to the box, but always step down from it.

Thanks for the idea, MMM! I used your pic of the box you built and posted it on craigslist, just to see if there is any demand for these things in our area before building any (my husband is a good carpenter). So far, a gym contacted me and has ordered 4 of them – NICE!!

MMM, have you ever thought about a YouTube channel as an addition to the blog? I enjoy your writing, but a project like this would be greatly enhanced with video. It’s easy to get out the “don’t buy shit” message without it, but all the welding, plumbing, carpentry, and even biking articles lend themselves to video.

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